scholarly journals Real time chemical characterization of local and regional nitrate aerosols

2009 ◽  
Vol 9 (11) ◽  
pp. 3709-3720 ◽  
Author(s):  
M. Dall'Osto ◽  
R. M. Harrison ◽  
H. Coe ◽  
P. I. Williams ◽  
J. D. Allan
Keyword(s):  
Organic Carbon ◽  
Mass Spectrometer ◽  
Western Europe ◽  
Time Of Flight ◽  
Chemical Characterization ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Neural Network Algorithm ◽  
Pm2.5 And Pm10

Abstract. Nitrate aerosols make a very major contribution to PM2.5 and PM10 in western Europe, but their sources and pathways have not been fully elucidated. An Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) and a Compact Time of Flight Aerosol Mass Spectrometer (C-ToF-AMS) were deployed in an urban background location in London, UK, collecting data as part of the REPARTEE-I experiment. During REPARTEE-I, daily PM10 concentrations ranged up to 43.6 μg m−3, with hourly nitrate concentrations (measured by AMS) of up to 5.3 μg m−3. The application of the ART-2a neural network algorithm to the ATOFMS data characterised the nitrate particles as occurring in two distinct clusters (i.e. particle types). The first (33.6% of particles by number) appeared to be locally produced in urban locations during nighttime, whilst the second (22.8% of particles by number) was regionally transported from continental Europe. Nitrate in locally produced aerosol was present mainly in particles smaller than 300 nm, whilst the regional nitrate presented a coarser mode, peaking at 600 nm. In both aerosol types, nitrate was found to be internally mixed with sulphate, ammonium, elemental and organic carbon. Nitrate in regional aerosol appeared to be more volatile than that locally formed. During daytime, a core of the regionally transported nitrate aerosol particle type composed of organic carbon and sulphate was detected.

scholarly journals Real time chemical characterization of local and regional nitrate aerosols

2008 ◽  
Vol 8 (6) ◽  
pp. 19457-19486
Author(s):  
M. Dall'Osto ◽  
R. M. Harrison ◽  
H. Coe ◽  
P. I. Williams ◽  
J. D. Allan
Keyword(s):  
Organic Carbon ◽  
Mass Spectrometer ◽  
Western Europe ◽  
Time Of Flight ◽  
Chemical Characterization ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Neural Network Algorithm ◽  
Pm2.5 And Pm10

Abstract. Nitrate aerosols make a very major contribution to PM2.5 and PM10 in western Europe, but their sources and pathways have not been fully elucidated. An Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) and a Compact Time of Flight Aerosol Mass Spectrometer (C-ToF-AMS) were deployed in an urban background location in London, UK, collecting data as part of the REPARTEE-I experiment. During REPARTEE-I, daily PM10 concentrations ranged up to 43.6 µg m−3, with hourly nitrate concentrations (measured by AMS) of up to 5.3 µg m−3. The application of the ART-2a neural network algorithm to the ATOFMS data characterised the nitrate particles as occurring in two distinct clusters (i.e. particle types). The first (33.6% of particles by number) appeared to be locally produced in urban locations during nighttime, whilst the second (22.8% of particles by number) was regionally transported from continental Europe. Nitrate in locally produced aerosol was present mainly in particles smaller than 300 nm, whilst the regional nitrate presented a coarser mode, peaking at 600 nm. In both aerosol types, nitrate was found to be internally mixed with sulphate, ammonium, elemental and organic carbon. Nitrate in regional aerosol appeared to be more volatile than that locally formed. During daytime, a core of the regionally transported nitrate aerosol particle type composed of organic carbon and sulphate was detected.

Chemical characterization of fine particulate matter, and source apportionment of organic aerosol at three sites in New Delhi, India

2020 ◽  
Author(s):  
Sachchida Tripathi ◽  
Vipul Lalchandani ◽  
Varun Kumar ◽  
Anna Tobler ◽  
Navaneeth Thamban ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Mass Spectra ◽  
Fine Particulate Matter ◽  
Time Of Flight ◽  
Chemical Characterization ◽  
New Delhi ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Fine Particulate

<p>Atmospheric particulate matter has adverse effects on human health, and causes over 4 million deaths per year globally. New Delhi was ranked as world’s most polluted megacity with annual average PM<sub>2.5</sub> concentration of ~140 ug.m<sup>-3</sup>. Thus, real time chemical characterization of fine particulate matter and identification of its sources is important for developing cost effective mitigation policies.</p><p>Highly time resolved real-time chemical composition of PM<sub>2.5</sub> was measured using Long-Time of Flight-Aerosol Mass Spectrometer (L-ToF-AMS) at Indian Institute of Technology Delhi and Time of Flight-Aerosol Chemical Speciation Monitor (ToF-ACSM) at Indian Institute of Tropical Meteorology, Delhi, and PM<sub>1 </sub>using High Resolution-Time of Flight-Aerosol Mass Spectrometer (HR-ToF-AMS) at Manav Rachna International University, Faridabad, Haryana located ~40 km downwind of Delhi during Jan-March, 2018. Black carbon concentration was measured using Aethalometer at all three sites. Unit mass resolution (UMR) and high resolution (HR) data analysis were performed on AMS and ACSM mass spectra to calculate organics, nitrate, sulfate and chloride concentrations. Positive Matrix Factorization (PMF) (Paatero and Tapper, 1994) of organic mass spectra was performed by applying multilinear engine (ME-2) algorithm using Sofi (Source finder) for identifying sources of OA.</p>

scholarly journals Characterization of the sources and processes of organic and inorganic aerosols in New York City with a high-resolution time-of-flight aerosol mass spectrometer

2010 ◽  
Vol 10 (10) ◽  
pp. 22669-22723 ◽  
Author(s):  
Y.-L. Sun ◽  
Q. Zhang ◽  
J. J. Schwab ◽  
K. L. Demerjian ◽  
W.-N. Chen ◽  
...  
Keyword(s):  
New York ◽  
New York City ◽  
High Resolution ◽  
Mass Spectrometer ◽  
York City ◽  
Time Of Flight ◽  
Resolution Time ◽  
Aerosol Mass Spectrometer ◽  
Spectral Pattern ◽  
Aerosol Mass

Abstract. Submicron aerosol particles (PM1) were measured in-situ using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) during the summer 2009 Field Intensive Study at Queens College in New York City. Organic aerosol (OA) and sulfate are the two dominant species, accounting for 54% and 24%, respectively, of total PM1 mass on average. The average mass size distribution of OA presents a small mode peaking at ~150 nm (Dva) in addition to an accumulation mode (~550 nm) that is internally mixed with sulfate, nitrate, and ammonium. The diurnal cycles of sulfate and OA both show pronounced peaks between 01:00–02:00 p.m. EST due to photochemical production. The average (±1σ) oxygen-to-carbon (O/C), hydrogen-to-carbon (H/C), and nitrogen-to-carbon (N/C) ratios of OA in NYC are 0.36 (±0.09), 1.49 (±0.08), and 0.012(±0.005), respectively, corresponding to an average organic mass-to-carbon (OM/OC) ratio of 1.62(±0.11). Positive matrix factorization (PMF) of the high resolution mass spectra identified five OA components: a hydrocarbon-like OA (HOA), two types of oxygenated OA (OOA) including a low-volatility OOA (LV-OOA) and a semi-volatile OOA (SV-OOA), a cooking-emission related OA (COA), and a unique nitrogen-enriched OA (NOA). HOA appears to represent primary OA (POA) from urban traffic emissions. It comprises primarily of reduced species (H/C=1.83; O/C=0.06) and shows a mass spectral pattern very similar to those of POA from fossil fuel combustion, and correlates tightly with traffic emission tracers including elemental carbon and NOx. LV-OOA, which is highly oxidized (O/C=0.63) and correlates well with sulfate, appears to be representative for regional, aged secondary OA (SOA). SV-OOA, which is less oxidized (O/C=0.38) and correlates well with non-refractory chloride, likely represents less photo-chemically aged, semi-volatile SOA. COA shows a similar spectral pattern to the reference spectra of POA from cooking emissions and a distinct diurnal pattern peaking around local lunch and dinner times. In addition, NOA is characterized with prominent CxH2x+2N+ peaks likely from amine compounds. Our results indicate that cooking-related activities are a major source of POA in NYC, releasing comparable amounts of POA as traffic emissions. POA=HOA+COA) on average accounts for ~30% of the total OA mass during this study while SOA dominates the OA composition with SV-OOA and LV-OOA on average accounting for 34% and 30%, respectively, of the total OA mass. The chemical evolution of SOA in NYC involves a~continuous oxidation from SV-OOA to LV-OOA, which is further supported by a gradual increase of O/C ratio and a simultaneous decrease of H/C ratio in total OOA. Detailed analysis of NOA (5.8% of OA) presents evidence that nitrogen-containing organic species such as amines might have played an important role in the atmospheric processing of OA in NYC, likely involving acid-base chemistry. Analysis of air mass trajectories and satellite imagery of aerosol optical depth (AOD) indicates that the high potential source regions of secondary sulfate and aged OA are mainly located in regions to the west and southwest of the city.

scholarly journals Characterization of a real-time tracer for isoprene epoxydiols-derived secondary organic aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements

2015 ◽  
Vol 15 (20) ◽  
pp. 11807-11833 ◽  
Author(s):  
W. W. Hu ◽  
P. Campuzano-Jost ◽  
B. B. Palm ◽  
D. A. Day ◽  
A. M. Ortega ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Secondary Organic Aerosol ◽  
Transport Model ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Chemical Transport Model ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Multiple Field

Abstract. Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products of isoprene mainly under low-NO conditions. Total IEPOX-SOA, which may include SOA formed from other parallel isoprene oxidation pathways, was quantified by applying positive matrix factorization (PMF) to aerosol mass spectrometer (AMS) measurements. The IEPOX-SOA fractions of organic aerosol (OA) in multiple field studies across several continents are summarized here and show consistent patterns with the concentration of gas-phase IEPOX simulated by the GEOS-Chem chemical transport model. During the Southern Oxidant and Aerosol Study (SOAS), 78 % of PMF-resolved IEPOX-SOA is accounted by the measured IEPOX-SOA molecular tracers (2-methyltetrols, C5-Triols, and IEPOX-derived organosulfate and its dimers), making it the highest level of molecular identification of an ambient SOA component to our knowledge. An enhanced signal at C5H6O+ (m/z 82) is found in PMF-resolved IEPOX-SOA spectra. To investigate the suitability of this ion as a tracer for IEPOX-SOA, we examine fC5H6O (fC5H6O= C5H6O+/OA) across multiple field, chamber, and source data sets. A background of ~ 1.7 ± 0.1 ‰ (‰ = parts per thousand) is observed in studies strongly influenced by urban, biomass-burning, and other anthropogenic primary organic aerosol (POA). Higher background values of 3.1 ± 0.6 ‰ are found in studies strongly influenced by monoterpene emissions. The average laboratory monoterpene SOA value (5.5 ± 2.0 ‰) is 4 times lower than the average for IEPOX-SOA (22 ± 7 ‰), which leaves some room to separate both contributions to OA. Locations strongly influenced by isoprene emissions under low-NO levels had higher fC5H6O (~ 6.5 ± 2.2 ‰ on average) than other sites, consistent with the expected IEPOX-SOA formation in those studies. fC5H6O in IEPOX-SOA is always elevated (12–40 ‰) but varies substantially between locations, which is shown to reflect large variations in its detailed molecular composition. The low fC5H6O (< 3 ‰) reported in non-IEPOX-derived isoprene-SOA from chamber studies indicates that this tracer ion is specifically enhanced from IEPOX-SOA, and is not a tracer for all SOA from isoprene. We introduce a graphical diagnostic to study the presence and aging of IEPOX-SOA as a triangle plot of fCO2 vs. fC5H6O. Finally, we develop a simplified method to estimate ambient IEPOX-SOA mass concentrations, which is shown to perform well compared to the full PMF method. The uncertainty of the tracer method is up to a factor of ~ 2, if the fC5H6O of the local IEPOX-SOA is not available. When only unit mass-resolution data are available, as with the aerosol chemical speciation monitor (ACSM), all methods may perform less well because of increased interferences from other ions at m/z 82. This study clarifies the strengths and limitations of the different AMS methods for detection of IEPOX-SOA and will enable improved characterization of this OA component.

scholarly journals Characterization of an aerodynamic lens for transmitting particles greater than 1 micrometer in diameter into the Aerodyne aerosol mass spectrometer

2013 ◽  
Vol 6 (11) ◽  
pp. 3271-3280 ◽  
Author(s):  
L. R. Williams ◽  
L. A. Gonzalez ◽  
J. Peck ◽  
D. Trimborn ◽  
J. McInnis ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Transmission Efficiency ◽  
Cfd Modeling ◽  
Operating Pressure ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Valve Assembly ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Abstract. We have designed and characterized a new inlet and aerodynamic lens for the Aerodyne aerosol mass spectrometer (AMS) that transmits particles between 80 nm and more than 3 μm in vacuum aerodynamic diameter. The design of the inlet and lens was optimized with computational fluid dynamics (CFD) modeling of particle trajectories. Major changes include a redesigned critical orifice holder and valve assembly, addition of a relaxation chamber behind the critical orifice, and a higher lens operating pressure. The transmission efficiency of the new inlet and lens was characterized experimentally with size-selected particles. Experimental measurements are in good agreement with the calculated transmission efficiency.

Characterization of an Aerodyne Aerosol Mass Spectrometer (AMS): Intercomparison with Other Aerosol Instruments

2005 ◽  
Vol 39 (8) ◽  
pp. 760-770 ◽  
Author(s):  
N. Takegawa ◽  
Y. Miyazaki ◽  
Y. Kondo ◽  
Y. Komazaki ◽  
T. Miyakawa ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass
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